Seamless mobility for data sessions across multiple radio access networks, such as UTRAN, CDMA2000 and WLAN, is possible with IP-level macro mobility. For IPv4 networks, IP mobility is described in Internet Engineering Task Force (IETF) Request for Comment (RFC) 3344, which introduces three logical entities on IPv4 networks: Mobile IP client functionality on hosts; Foreign Agent (FA) functionality on designated routers on roaming/foreign networks; and, Home Agent (HA) functionality on a user's home IP network. The protocol defines a mechanism by which mobile IP compliant mobile terminals, or nodes, can maintain their network level association (i.e., IP address) while moving from network to network, essentially maintaining seamless transport sessions across network boundaries. The centerpiece of the protocol is the services provided by a designated router at the home network called a Home Agent. The Home Agent provides the services of seamless mobility to registered mobile nodes while away from the home network. The Home Agent acts, essentially, as a default router for the mobile nodes while they are away from the home network. It intercepts all routed packets destined for roaming mobile nodes and tunnels them to the mobile nodes' current care-of-address, which resides in the FA.
There exists a problem, however, with the Mobile IPv4 Home Agent as specified in IETF RFC3344. The Home Agent as specified in IETF RFC3344 is a stateful router; i.e., it maintains a mobility bindings database for all registered mobile nodes while they are away from the home network. The mobility binding for a particular mobile node is a data structure containing, minimally, the mobile node's home IP address, current care-of-address (i.e., FA IP address), mobility lifetime and other mobile node specific information. The Home Agent, however, can be a single-point-of-failure from the point of view of Mobile IP operation; i.e., if the Home Agent fails, all on-going mobile IP sessions supported by the failed Home Agent will be lost; there is no redundancy or resiliency solution in the Mobile IP protocol.
Accordingly, there is a need in the art for improved apparatus and methods for Home Agent resiliency for Mobile Internet Protocol (IP) Version 4 (MIPv4). Preferably, such apparatus and methods will utilize the existing hardware infrastructure associated with conventional communications networks, thereby reducing the cost of implementing such improved systems and methods.